docstr: Test get_multiplexed_model_id() API
docstr_tok: ["Test","get_multiplexed_model_id","(",")","API"]
code: def test_get_multiplexed_model_id(self):
      """Test get_multiplexed_model_id() API"""
      assert serve.get_multiplexed_model_id() == ""
      ray.serve.context._serve_request_context.set(
          ray.serve.context._RequestContext(multiplexed_model_id="1")
      )
      assert serve.get_multiplexed_model_id() == "1"
  
imports: import asyncio
  import os
  from typing import List
  import pytest
  import requests
  import ray
  from ray import serve
  from ray._private.test_utils import SignalActor, wait_for_condition
  from ray._private.utils import get_or_create_event_loop
  from ray.serve._private.constants import SERVE_MULTIPLEXED_MODEL_ID
  from ray.serve.context import _get_internal_replica_context
  from ray.serve.handle import RayServeHandle
  from ray.serve.multiplex import _ModelMultiplexWrapper
label_desc: Use image node_id 2 for calling the TestBasicAPI obj's underlying member method code with example usage: obj.test_get_multiplexed_model_id() without return types